1. Field of the Invention
This invention relates to a controller for a Hall effect sensor for changing output characteristics, particularly the hysteresis width, of the Hall effect sensor.
2. Description of the Background Art
Among the sensors for detecting the displacement or position of objects, there is a Hall effect sensor which uses a Hall element. For example, as the Hall effect sensor element there is a Hall IC. Such a Hall effect sensor uses a permanent magnet or the like disposed on an object and detects the position or displacement of the object by converting the change in magnetic flux density varying in correspondence to the movement of the object into an output voltage change.
For example, when a Hall IC receives a magnetic flux density above an operating magnetic flux density, it provides a "low" output voltage, i.e., an "on" signal. On the other hand, when it receives a magnetic flux density below a restoration magnetic flux density, it provides a "high" output voltage, i.e., an "off" signal.
In the above Hall IC or like Hall effect sensor, a hysteresis, which has a hysteresis width between the operating magnetic flux density and the restoration magnetic flux density, is set in its output characteristic in order to prevent the phenomenon of chattering. Therefore, the Hall IC or like Hall effect sensor can not provide the "on" and "off" signals unless the magnetic flux density is varied beyond the hysteresis width noted above. This means that if the displacement of the object with a permanent magnet, for instance, set thereon is small, it can not be detected with the Hall IC.